bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonViewerSorter.java

/***************************************************************************************************
 * Copyright (c) 2006 IBM Corporation and others. All rights reserved. This program and the
 * accompanying materials are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * 
 * Contributors: IBM Corporation - initial API and implementation
 **************************************************************************************************/

package org.eclipse.ui.navigator;

import java.util.Set;

import org.eclipse.jface.viewers.TreePath;
import org.eclipse.jface.viewers.TreePathViewerSorter;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerSorter;
import org.eclipse.ui.internal.navigator.NavigatorContentService;

/**
 * 
 * Provides an implementation of TreeViewerSorter that uses the given parent to determine the
 * correct sort order based on the defined
 * <b>org.eclipse.ui.navigator.navigatorContent/navigatorContent/commonSorter</b> elements
 * available in the set of <i>visible</i> content extensions.
 * 
 * <p>
 * The CommonViewerSorter must be assigned a {@link INavigatorContentService} to drive its sorting
 * algorithm. Without a vaild content service, the sorter will return the default ordering.
 * </p>
 * <p>
 * A CommonViewerSorter may not be attached to more than one CommonViewer.
 * </p>
 * 
 * <p>
 * Clients may not extend this class.
 * </p>
 * 
 * 
 * 
 * @since 3.2
 * 
 */
public final class CommonViewerSorter extends TreePathViewerSorter {

	private NavigatorContentService contentService;

	private INavigatorSorterService sorterService;

	/**
	 * Create a sorter service attached to the given content service.
	 * 
	 * @param aContentService
	 *            The content service used by the viewer that will use this sorter service.
	 */
	protected void setContentService(NavigatorContentService aContentService) {
		contentService = aContentService;
		sorterService = contentService.getSorterService();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.ViewerSorter#category(java.lang.Object)
	 */
	public int category(Object element) {
		if (contentService == null)
			return 0;

		INavigatorContentDescriptor source = contentService.getSourceOfContribution(element);
		if (source == null)
			source = getSource(element);
		return source != null ? source.getPriority() : Priority.NORMAL_PRIORITY_VALUE;
	}

	public int compare(Viewer viewer, TreePath parentPath, Object e1, Object e2) {
		if (contentService == null)
			return -1;
		INavigatorContentDescriptor sourceOfLvalue = contentService.getSourceOfContribution(e1);
		INavigatorContentDescriptor sourceOfRvalue = contentService.getSourceOfContribution(e2);

		if (sourceOfLvalue == null)
			sourceOfLvalue = getSource(e1);
		if (sourceOfRvalue == null)
			sourceOfRvalue = getSource(e2);

		// identity comparison
		if (sourceOfLvalue != null && sourceOfLvalue == sourceOfRvalue) {
			Object parent;
			if (parentPath == null) {
				parent = viewer.getInput();
			} else {
				parent = parentPath.getLastSegment();
			}
			ViewerSorter sorter = sorterService.findSorter(sourceOfLvalue, parent, e1, e2);
			if (sorter != null) {
				return sorter.compare(viewer, e1, e2);
			}
		}
		int categoryDelta = category(e1) - category(e2);
		if (categoryDelta == 0) {
			return super.compare(viewer, e1, e2);
		}
		return categoryDelta;
	}

	private INavigatorContentDescriptor getSource(Object o) {
		Set descriptors = contentService.findDescriptorsWithPossibleChild(o);
		if (descriptors != null && descriptors.size() > 0) {
			return (INavigatorContentDescriptor) descriptors.iterator().next();
		}
		return null;
	}

}